1. Field of the Invention
The present invention relates to a solid-state imaging device, a manufacturing method of the solid-state imaging device and an electronic apparatus, and particularly relates to a solid-state imaging device having a waveguide structure, a manufacturing method of the waveguide structure and an electronic apparatus having the solid-state imaging device.
2. Description of the Related Art
A solid-state imaging device, for example, a CMOS-type solid-state imaging device (hereinafter, referred to as “CMOS image sensor”) has a feature in which peripheral circuits such as a DSP (Digital Signal Processor) can be mounted on the same chip (substrate) by utilizing a CMOS process. When peripheral circuits are mounted on the same circuit, there is a case where a multilevel interconnection structure such as four-layered structure concerning wiring is used for reducing the scale of peripheral circuits.
However, since the distance between a substrate surface (silicon interface) to a micro lens (on-chip lens) is increased in the case where the multilevel interconnection structure is used, light condensing efficiency when light which is incident through the micro lens is condensed (introduced) on a light receiving surface of a light receiving portion (photoelectric conversion portion) is reduced. When the light condensing efficiency is reduced, pixel sensitivity is reduced.
Accordingly, a so-called waveguide structure is known, in which a waveguide is provided at the center of the pixel, thereby confining light within the waveguide to reduce the light amount loss in an optical path leading to the light receiving portion from the micro lens in order to increase the light condensing efficiency and to improve pixel sensitivity.
In related art, in order to introduce light to the light receiving portion more efficiently, a waveguide structure having a forward-tapered shape portion in which the size of a planer shape seen from a light incident direction is decreased gradually from a surface of the light incident side to the light receiving portion side is proposed (for example, refer to JP-A-2004-221532 (Patent Document 1). Moreover, a structure in which an aperture at an upper portion of the tapered shape portion (entrance side) of a tapered shape portion is largely opened to thereby increase the incident light amount as compared with the waveguide structure described in Patent Document 1 is proposed (for example, refer to JP-A-2008-103757 (Patent Document 2)).